code: def test_stateful_module(self):
      c = flax_module.Module.create(Counter)
      rng = jax.random.PRNGKey(42)
      variables = c.init(rng)
      self.assertEqual(variables, {"state": {"counter": {"c": 0}}})
  
      for i in range(10):
          out, variables = c.apply(variables, mutable=["state"])
          self.assertEqual(out, i)
          self.assertEqual(
              variables, {"state": {"counter": {"c": i + 1}}}
          )
  
imports: from absl.testing import absltest
  from absl.testing import parameterized
  import flax.linen
  from haiku._src import base
  from haiku._src import filtering
  from haiku._src import module
  from haiku._src import transform
  from haiku._src.flax import flax_module
  from haiku._src.flax import utils
  from haiku._src.nets import resnet
  import jax
  import jax.numpy
  import numpy
label_desc: Use image node_id 4 for calling the FlaxModuleTest obj's underlying member method code with example usage: obj.test_stateful_module() without return types